Abstract Within the past decade, child endangerment laws have become a new component in protecting underage passengers. Driving while impaired and/or recklessly with a child in the car falls under this definition. Yet 9 of 51 U.S. jurisdictions have not enacted policies protecting young passengers from their drinking drivers. Recent studies conducted by this research team found driving under the influence (DUI) with a child in the car to be a persistent and dangerous behavior, which extant DUI-child endangerment (CE) laws have failed to alleviate. Many reasons for the ineffectiveness of DUI-CE laws have been postulated, including the use of DUI-CE laws in courts as a plea-bargain tool, a lack of awareness of the law, and a lack of understanding of the risks involved. Such a lack of knowledge has impeded the design of effective interventions and countermeasures, including making corrections to extant DUI-CE laws to make them effective. This application aims to close this gap in knowledge. To do so, we will take advantage of two unique databases. Run and maintained by Mothers Against Drunk Driving (MADD), the Court Monitoring database is a unique database that keeps records of court actions and dispositions involving DUI violations. By accessing this database, we will be able to assess how drivers who drink while driving with children are treated in court and, particularly, how DUI-CE laws are applied to them. MADD also runs and maintains a phone help line that keeps excellent records of callers reaching out to MADD for help. From this database, we will access callers concerned about DUI-CE offenses who have been assisted by MADD. We will invite a select group of callers to participate in a one-on-one interview aimed at qualitatively understanding the environment and reasons why some adults drive with children while impaired. To achieve this goal, we have assembled a strong team of researchers, including Drs. Romano and Kelley- Baker (traffic safety experts who are leading researchers in DUI-CE events), Dr. Thomas (a legal expert in alcohol- and drug-related traffic laws), and Drs. Dunn and Tefft, whose expertise on the application of Levitt & Porter?s approach to traffic safety will allow us to estimate, for the first time, the prevalence of DUI-CE in the country and subsequently assess how much of the information to be obtained from MADD?s databases can be generalized to the whole population. We are certain that the outcome of this exploratory study will be crucial to move the DUI-CE research agenda forward.